Detergent composition



United States Patent Ofifice 3,017,363 DETERGENT l-JIEMPGSITION .lames H. Wilson, Demarest, NJ, assignor to Lever Brothers Company, New York, N.Y., a corporation of Maine N Drawing. Filed Aug. 28, 1958, Ser. No. 757,702 6 Claims. (Cl. 252152) This invention relates to detergent compositions having improved foam stability. In particular, the invention is concerned with the use of a combination of specific alkyl aryl sulfonates in detergent compositions, the combination providing washing solutions of greatly improved foam stability.

The problem of foam stability in washing solutions prepared from detergent compositions is one which has received a great deal of attention by the detergent industry. Thus, it has become common practice to include foam stabilizing additives in detergent compositions to improve the persistence and stability of the foam produced by agitation of a washing solution containing the composition. Examples of well-known foam stabilizing additives include fatty alcohols, such as lauric alcohol, fatty acid substituted amides, such as lauric diethanol amide and lauric isopropanol amides, and a compound containing a phenolic hydroxyl group such as parahydroxy laurophenone.

The importance of the foam stability of washing solutions containing detergents stems from consumer attitudes and beliefs. The housewife generally uses the presence of foam as an index of the cleansing ability of the solution. Collapse and disappearance of foam indicates to the housewife that the fat-emulsifying and other cleansing ability of the solution have been used up. Under certain circumstances, this is not true, as detergent solutions may retain their cleansing ability or detergent action long after the foam has disappeared. Conversely, some detergent solutions may retain their foam long after the cleansing ability thereof has disappeared. It is generally the aim of detergent manufacturers to obtain detergent compositions which, when employed in a washing solution, maintain a consistent relationship between the presence of sudsand detergency. It is the compositions in which the detergency outlasts the suds that foam stabilizers are required.

It has now been found that a detergent composition containing a water-soluble salt of dodecyl benzene sulfonic acid and a water-soluble salt of pentadecyl benzene sulfonic acid in a ratio of 1:1 by weight provides a very marked increase in foam stability of washing solutions containing such a detergent. In addition, the detergent composition containing the 1:1 mixture also for-ms a very much more stable emulsion of fatty materials.

The water-soluble salts of dodecyl and pentadecyl benzene sulfonic acid belong to a class of detergents wellknown in the art as alkyl aryl sulfonates. The preferred compounds of this invention are sulfonated phenylpolypropylene alkanes, characterized by the branched chain structure of polypropylene and a tertiary alkyl carbon at Patented Jan. 16, 1962 the benzene ring and having the following structure:

CHzRg souu where M is hydrogen, an alkali metal or an organic amine cation, and R and R are alkyl, of the type formula C H and at least one R is a polypropylene group, the whole alkyl group containing an average of 12 carbon atoms in the case of the dodecyl salts and an average of 15 carbon atoms in the case of the pentadecyl salts. These are known compositions whose preparation and properties are set forth in US. Patent No. 2,477,383 to Lewis, issued July 26, 1949.

As explained in the above-identified patent, the polymerization reaction by which the alkyl substituents are obtained does not proceed so smoothly or accurately as to yield only exact tetraor penta-mutiples of the propylene reactant. Therefore, the sulfonates of this invention are not pure chemical compounds, but are mixtures, the major portions of which have the characteristic C or C polypropylene substituent. As used throughout this specification, the terms dodecyl and pentadecy are meant to be descriptive of the separate C and C polypropylene fractions described in the Lewis patent. In other words, the water-soluble salt of dodecyl benzene sulfonic acid of this invention is the neutralized sulfonated alkyl benzene prepared by alkylating benzene with a C polymer fraction obtained according to column 8, lines 18-43 of the Lewis patent, followed by sulfonation and neutralization. The water-soluble salt of pentadecyl benzene sulfonic acid of this invention is obtained by sulfonation and neutralization of an alkyl benzene prepared by alkylatio of benzene with the C polymer fraction described in column 8, lines 1843 of the Lewis patent. The C fraction is stated to have a boiling range of from about 330 F. to about 420 F., and at least about 50% of the fraction boils above 350 F. The C fraction, on the other hand, is stated to have a boiling range of from about 420 F. to about 510 F., and at least ahout 50% of this fraction boils above 450 F.

As aforementioned, any of the water-soluble salts of dodecyl benzene sulfonic acid and pentadecyl benzene sulfonic acid may be employed. The invention will be described hereinafter in terms of the preferred ammonium salt. However, other salts, such as potassium and sodium salts may be employed to equal advantage.

In the detergent compositions of this invention, it is important that the ammonium dodecyl benzene sulfonate and the ammonium pentadecyl benzene sulfonate be present in approximately equal quantities; that is, in the ratio of about 1 :1 by weight. For some reason not fully understood by the applicant, this proportion is critical and combination of the ingredients in any other proportion, such as 3:1 or 1:3 or even 3:2 or 2:3, does not provide the greatly improved suds stability of the 1:1 proportion. This is shown clearly in Table I below, which gives data obtained by evaluating various proportions of the two active detergent ingredients in terms of their suds stability.

TABLE I Evaluation of mixtures of the ammonium salt 0] pentadecylbenzenesulfonic acid and/or dadecylbenzenesulfonic acid Formula designation 1 2 3 4 5 6 7 Proportion, by weight 3:1 1:1 1:3 3:2 2:3 Percent pentadecylhenzenesultonic acid 14.. 13 9. 42 4. 71 11. 30 7. 54 Percent dodecylbenzenesult'onic acid 81 16 8 11. 8&1). 14g 8;. Percent NHQHY PH m 1657) m m 100. 00 m Dishwashing data: Number of plates washed in 120 p.p.rn. hardness water at a detergent level of 8 gins. (2 deter.) 12, 13 13, 14 22, 23 22, 22 16, 18 Dishpan suds stability test: Time for suds to break (secs) (avg. 2

deter.)-- 23 50 148 60 33 The dishpan suds stability test is a standard test for determining the stability of suds in the presence of sudsdestroying agents. In conducting the test, grams of the detergent sample is dissolved in six quarts of tap water at 120 F. in a dishpan of standard size. grams of tallow containing 15% of free fatty acids are added and the solution is agitated for seconds. The time for the suds to completely disappear is then determined in seconds, and these are the values given above. It is noted that fatty acids are particularly effective in destroying foam and that for this reason, the test employs a tallow having a high free fatty acid content.

A standard dishwashing test was employed evaluating the detergents of Table I. The standard dishwashing test measures the number of artificially soiled dinner plates washed with the detergent under standard conditions. The standard soil employed is a uniform blend of 9 parts by weight of emulsifier-free vegetable shortening, 8 parts by weight of bread flour, and green color. A teaspoonful of the standard soil is spread evenly over each plate. Six quarts of water of the desired hardness is adjusted to 116 F. and a measured amount of detergent is added. The number of standardly soiled plates washed in this solution according to a standardized washing technique gives an indication of the effectiveness of the solution. The end point is reached when the foam no longer completely covers the surface of the washing solution.

It will be seen from Table I that a very significant improvement in suds stability was obtained only where the two active ingredients are present in the ratio of 1:1. In the dishwashing test, improvement was shown in Formula No. 4, where the pentadecyl salt and dodecyl salt were present in a ratio of 1:3, as well as Formula No.

4 TABLE IIContinued PERCENT OIL SEPARATION AFTER 3 HOURS It will be noted from Table 11 above that the most stable oil emulsion was obtained with Formula N0. 3 where the proportion of active ingredients was 1:1.

Table III below shows a series of light-duty liquid detergents. Formula C represents an example of a d tergent composition prepared according to this invention. The other formulae presented provide a comparison of several detergent formulations with the composi- 3, Where the salts were present in equal quantities. No tion of this invention on the basis of suds stability.

TABLE III Formula designation A B C D E F G Percent 1 pentadecyl benzene sulfonic acid act 16. 28 8.14 12. 21 4. 07 9. 77 6.51 Percent dodecyl benzene sulfonic acid, act: 16. 28 8.14 4. 07 12.21 6. 51 77 Percent lauric diethanol amide.... 5.00 5.00 5. 00 5. 00 5. 00 5.00 5. 00 Percent Alipalfl act. ll. 87 11. 87 11.87 11. 87 11. 87 11. 87 Percent ethyl alcohol 12.00 12.00 12.00 12.00 12.00 12. 0O 1 54. 85 54. 85 54. 85 54. 85 54. 85 54. 85 54. 85 Percent t r, l H and er nts 100 00 00 TL 00 00 00 10a 00 100 O0 Dish an suds stabilit test: Time for suds to break (sees. (avg. 2

(let n) .3. 75 65 178 88 90 95 105 1 All percentages are by Weight.

2 Alipal is a trade name for the ammonium salt of sulfated nonyl phenol condensed with 4 moles of ethylene oxide.

improvement in suds stability was shown for the 1:3 ratio detergent, however.

The following table gives the results of a series of tests which were conducted for the purpose of determining the ability of the compositions of Table I to emulsify oil. A series of levels of detergents ranging from 1 to 2 cc. were employed with 20 cc. of Wesson oil. Water at 116 F. was added to bring the total volume of the mixture to 500 cc. The cylinder containing the solution was inverted ten times and the emulsion thereafter transferred to an open beaker for evaluation. The percent of oil separation was determined after 1, 3, 5 and 24 hours.

TABLE II PERCENT 01L SEPARATION AFTER 1 HOUR Formula 1 cc. deter- 1% cc. de- 2 cc. detergent tergent gent 90 50 Trace 50 30 Trace 25 5 Trace 50 30 Trace 5O Trace 50 30 Trace 55 25 Trace Formulae A and B represent prior art detergent compositions wherein either one or the other of the active ingredients are employed exclusively. It will be noted that the improvement in foam stability obtained in Formula C, the composition of this invention, is nearly three times greater than the suds stability of the A and B compositions. The suds stability obtained in Formulae D through G represent a slight improvement over Formulae A and B, but the results are nowhere near as startling as that obtained in Formula C where the active ingredients are present in the critical 1:1 ratio.

It is understood that the foregoing examples are illustrative only and that modifications will occur to those skilled in the art. Although the invention is illustrated in terms of a light duty liquid detergent, it is recognized that the detergent combination of this invention may be advantageously employed in other types of detergent compositions, such as heavy duty liquid detergents and detergents in powder form. Therefore, the invention is not to be limited to the examples given, but is defined by the appended claims.

I claim:

1. A detergent composition consisting essentially of a soluble salt of pentadccyl benzene sulfonic acid and a soluble salt of dodecyl benzene sulfonic acid, the two salts being present in the composition in the proportion of about 1:1 by weight.

2. A detergent composition consisting essentially of sodium pentadecyl benzene sulfonate and sodium dodecyl benzene sulfonate in the ratio of about 1:1 by weight.

3. A detergent composition consisting essentially of ammonium pentadecyl benzene sulfonate and ammonium dodecyl benzene sulfonate in the ratio of about 1:1 by weight.

4. A detergent composition consisting essentially of a soluble salt of pentadecyl benzene sulfonic acid, a soluble salt of dodecyl benzene sulfonic acid, a detergent solubilizing agent, and Water, said salts being present in a ratio of about 1:1 by weight and said solubilizing agent and water each being present in an amount sufiicient to provide a clear liquid composition at room temperature.

5. A detergent composition consisting essentially of a water-soluble salt of a 1:1 mixture of (1) a sulfonated monophenyl-substituted propylene tetramer, the alkyl substituent of which is a C polypropylene fraction having a boiling range of from about 330 F. to about 420 F., at least about 50% of which boils above 350 F., and (2) a sulfonated monophenyl-substituted propylene pentamer, the alkyl substituent of which is a C polypropylene fraction having a boiling range of from about 420 F. to about 510 F., at least about of which boils above 450 F.

6. A detergent composition consisting essentially of ammonium pentadecyl benzene sulfonate, ammonium dodecyl benzene sulfonate, lauric diethanol amide, the ammonium salt of sulfonated nonyl phenol condensed with 4 moles of ethylene oxide, ethyl alcohol and water, the benzene sulfonates being present in a ratio of about 1:1 by weight, and the alcohol and water each being present in an amount suflicient to provide a clear liquid composition at room temperature.

References Cited in the file of this patent UNITED STATES PATENTS 2,477,383 Lewis July 26, 1949 2,607,740 Vitale et al. Aug. 19, 1952 FOREIGN PATENTS 729,531 Great Britain May 4, 1955 

1. A DETERGENT COMPOSITION CONSISTING ESSENTIALLY OF A SOLUBLE SALT OF PENTADECYL BENZENE SULFONIC ACID AND A SOLUBLE SALT OF DODECYL BENZENE SULFONIC ACID, THE TWO SALTS BEING PRESENT IN THE COMPOSITION IN THE PROPORTION OF ABOUT 1:1 BY WEIGHT.
 3. A DETERGENT COMPOSITION CONSISTING ESSENTIALLY OF AMMONIUM PENTADECYL BENZENE SULFONATE AND AMMONIUM DEDECYL BENZENE SULFONATE IN THE RATIO OF ABOUT 1:1 BY WEIGHT. 